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Fibre Concentration by Membrane Vacuum Filtration in Preparation for Rapid Microscopic Comparison

NCJ Number
139800
Journal
Canadian Society of Forensic Science Journal Volume: 25 Issue: 3 Dated: (September 1992) Pages: 177-181
Author(s)
R A Wickenheiser
Date Published
1992
Length
5 pages
Annotation
The use of clear, cellulose adhesive tape to gather forensically significant textile fibers has become the method of choice in recent years.
Abstract
While this technique facilitates the removal of extraneous fibers from exhibit materials, searching for and removing recovered fibers from cellulose still involve a tedious and time-consuming process. Questioned fibers are removed from cellulose tape and suspended in solution by dissolving tape adhesive. Membrane filtration under vacuum rapidly concentrates fibers on one filter disk. Fibers are then observed under a low-power microscope for screening, followed by direct mounting for rapid high-power microscopic viewing and comparison. Despite the fact that adhesive tape is the method of preference, it is not without some drawbacks. The method is time-consuming because each fiber must be removed from the tape and mounted individual. Many fibers may be mounted that do not match due to the low discrimination power of the first scan. In addition, fibers may often prove difficult to remove from the tape and may be lost or broken. Procedures and materials involved in the membrane vacuum filtration technique are outlined. 3 references and 1 photograph

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